Lithium-based energy-storage devices are used in a variety of consumer products. Examples of such devices include supercapacitors, ultracapacitors, and more commonly lithium cells and lithium-ion cells. Some lithium-based energy-storage devices are rechargeable and have relatively long useful lifetimes. Nevertheless, they eventually fail or are discarded prior to failure, and therefore contribute to a significant and growing waste stream. In view of this situation, environmental regulations, industry standards, and collection services have arisen to promote the recycling of lithium-based energy storage devices.
Current recycling procedures for lithium-ion rechargeable cells may include two general approaches, pyrometallurgy and hydrometallurgy. Pyrometallurgical processing utilizes high temperatures to decompose and melt materials within the lithium cells leading to the recovery of metallic cobalt, or cobalt containing alloys. Such processing techniques thus generally involve the decomposition of the active electrodes, casing, current collectors, packaging, and therefore require further steps to manufacture the positive electrode material from the recovered metallic cobalt, nickel and/or alloys. Hydrometallurgic decomposition of lithium cells utilizes strong acids or bases and leads to the recovery of cobalt salts through multistep processing and precipitation. Kim et. al. (J. Power Sources 132 (2004) 145) teach a variation of a hyrometallurgic process in which LixCoO2 from the spent battery is fully dissolved using a concentrated lithium hydroxide solution and precipitated again as hexagonal LiCoO2. However, such dissolution and precipitation requires the use of highly concentrated caustic chemicals.